Electrodes for stimulation leads and methods of manufacture and use

ABSTRACT

An electrode has a unitary ring with an exterior surface, interior surface, and at least two edges. The electrode also includes a seat formed in at least the exterior surface of the unitary ring. The seat is configured and arranged for attachment of a terminal end of a lead wire, disposed in the seat, to the electrode. A lead includes a lead body; a plurality of electrodes disposed at the distal end of the lead body; and a plurality of lead wires. Each electrode includes a unitary ring and a seat in the unitary ring. The unitary ring has an exterior surface and an interior surface and defines a hollow center region. The seat is formed as a depression of a portion of the unitary ring. Each of the lead wires extends along the lead body and is attached to a corresponding electrode at the seat of the corresponding electrode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/427,935, filed Apr. 22, 2009, now allowed, which claims the benefitof U.S. Provisional Patent Application Ser. No. 61/049,237, filed Apr.30, 2008, all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention is directed to electrodes and methods of making and usingthe electrodes. The invention is also directed to electrodes with a seatfor receiving a conductor, as well as stimulation devices containing theelectrodes and methods of manufacturing and using the electrodes andstimulation devices.

BACKGROUND OF THE INVENTION

Stimulation devices have been developed to provide therapy for a varietyof disorders, as well as for other treatments. For example, stimulationdevices can be used to stimulate nerves (such as the spinal cord),muscles, or other tissue. A stimulation device typically includes acontrol module (with a pulse generator), one or more leads, and an arrayof stimulator electrodes on each lead. The stimulator electrodes can beimplanted in contact with or near the nerves, muscles, or other tissueto be stimulated. The pulse generator in the control module generateselectrical pulses that are delivered by the electrodes to body tissue.As an example, electrical pulses can be provided to the dorsal columnfibers within the spinal cord to provide spinal cord stimulation.

The stimulator electrodes are coupled to the control module by the leadand the control module is typically implanted elsewhere in the body, forexample, in a subcutaneous pocket. The lead is often anchored at one ormore places in the body to prevent or reduce movement of the lead orstimulator electrodes within the body which could damage tissue, movethe stimulator electrodes out of the desired position, or interrupt theconnection between the stimulator electrodes and the control module.

BRIEF SUMMARY OF THE INVENTION

One embodiment is an electrode having a unitary ring with an exteriorsurface, an interior surface, and at least two edges. The electrode alsoincludes a seat formed in at least the exterior surface of the unitaryring. The seat is configured and arranged for attachment of a terminalend of a lead wire, disposed in the seat, to the electrode.

Another embodiment is a lead including a lead body; a plurality ofelectrodes disposed at the distal end of the lead body; and a pluralityof lead wires. Each electrode includes a unitary ring and a seat in theunitary ring. The unitary ring has an exterior surface and an interiorsurface and defines a hollow center region. The seat is formed as adepression of a portion of the unitary ring. Each of the lead wiresextends along the lead body and is attached to a corresponding electrodeat the seat of the corresponding electrode.

Yet another embodiment is a method of making a system for stimulation.The method includes providing an electrode having a unitary ring with anexterior surface, an interior surface, and a seat formed by depressing aportion of the unitary ring. A lead wire is disposed within the seat ofthe electrode and a terminal end of the lead wire is coupled to the seatof the electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

For a better understanding of the present invention, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, wherein:

FIG. 1 is a schematic view of one embodiment of a stimulator system,according to the invention;

FIG. 2 is a schematic side view of one embodiment of a lead, accordingto the invention;

FIG. 3 is a schematic perspective view of one embodiment of a lumentube, according to the invention;

FIG. 4 is a schematic cross-sectional view of the lumen tube of FIG. 3at line 4-4, according to the invention;

FIG. 5 is a schematic perspective view of one embodiment of anelectrode, according to the invention;

FIG. 6 is a schematic cross-sectional view of one embodiment of theelectrode of FIG. 5 at line 6-6, according to the invention;

FIG. 7 is a schematic front view of one embodiment of an electrode,according to the invention;

FIG. 8 is a schematic perspective view of another embodiment of anelectrode, according to the invention;

FIG. 9 is a schematic perspective view of a third embodiment of anelectrode, according to the invention;

FIG. 10 is a schematic perspective view of a fourth embodiment of anelectrode, according to the invention;

FIGS. 11A-C illustrate steps in a first method for partially assemblinga lead, according to the invention;

FIG. 12A-C illustrate steps in a second method for partially assemblinga lead, according to the invention; and

FIG. 13 is a schematic overview of components of one embodiment of asystem for stimulation, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to electrodes and methods of making and usingthe electrodes. The invention is also directed to electrodes with a seatfor receiving a conductor, as well as stimulation devices containing theelectrodes and methods of manufacturing and using the electrodes andstimulation devices.

FIG. 1 illustrates schematically an implantable stimulation device 100,such as a spinal cord stimulator. The implantable stimulation deviceincludes a control module 102, an electrode array 104, and a lead 106coupling the control module to the electrode array. It will beunderstood that the system for stimulation can include more, fewer, ordifferent components and can have a variety of different configurationsincluding those configurations disclosed in the stimulator referencescited herein. The control module 102 typically includes a pulsegenerator that provides pulses of stimulation current to electrodes ofthe electrode array 104. The control module 102 may also include a powersource for generating the stimulation current or may receive power froman external source. The power source can be any available power sourceincluding batteries, such as primary batteries or rechargeablebatteries. Examples of other power sources include, but are not limitedto, super capacitors, nuclear or atomic batteries, mechanicalresonators, infrared collectors, thermally-powered energy sources,flexural powered energy sources, bioenergy power sources, fuel cells,bioelectric cells, osmotic pressure pumps, and the like including thepower sources described in U.S. Pat. No. 7,437,193, incorporated hereinby reference.

The control module 102 is optionally programmable to allow programmingof one or more functions such as, for example, the selection ofelectrodes for stimulation, the selection of electrodes as anode orcathode, the amplitude of the stimulation current, the duration of thestimulation current, and the periodicity of the stimulation current. Insome embodiments, the control module 102 can be accessed using aprogramming unit external to the body of the patient to alter or modifythese functions.

The electrode array 104 typically includes one or more electrodes 110.In some embodiments, the electrode array 104 includes three, four, five,six, seven, eight, nine, ten or more electrodes 110. The electrodes aredisposed around the circumference of a lead, such as in a percutaneouslead.

The lead 106 includes a set of lead wires (for example, one lead wireper electrode of the electrode array) within a non-conductive sheathing.Each lead wire couples one or more electrodes to a terminal on theproximal end of the lead. The proximal end is inserted into the controlmodule where the terminals are coupled to contacts of the controlmodule. Non-limiting examples of suitable control modules and leads areillustrated in U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029;6,609,032; and 6,741,892, all of which are incorporated herein byreference.

The electrodes of the invention may be used with other commonstimulation devices including cardiac pacing leads, which typically mayhave one or two electrodes on the lead. Still other stimulation devicesinclude various implantable defribrillators.

FIG. 2 is a schematic representation of one embodiment of a lead 106.The lead 106 includes one or more electrodes 110. Preferably, theelectrodes 110 are separated from one another and are disposed in aspaced apart arrangement as illustrated schematically in FIG. 2. Thedistance between adjacent electrodes 110 may be relatively constantacross the electrode array as illustrated in FIG. 2. Alternatively, thedistances between adjacent electrodes 110 may vary.

The lead optionally includes spacers 182. Preferably, the spacers 182are disposed between the electrodes 110 as illustrated in FIG. 2. Thespacers 182 preferably have a hollow center area such that the spacers182 can be threaded onto a lumen tube 176 (see FIGS. 3 and 11) or can beused as a part of the lead body to separate the electrodes. The lead 106may also include an end spacer 184. The end spacer 184 is disposed atthe distal end of the lead 106. The end spacer 184 may have any shape,but is preferably rounded at the distal end as illustrated schematicallyin FIG. 2. The spacers 182 and the end spacer 184 can be made of anynon-conductive biocompatible material including, for example, silicone,polyurethane, and polyetheretherketone (PEEK). The spacers 182, 184 helpelectrically isolate the electrodes 110. Additionally or alternatively,the electrodes can be disposed over portions of a contiguous,non-conducting lead body with an opening through the lead body to allowthe conductor to be coupled to the electrode.

The outer diameter of the electrode 110 may be the same as the outerdiameter of the spacers 182, 184 of the lead 106 as illustrated in FIG.2. The outer diameter of the electrode 110 may alternatively be greaterthan the outer diameter of the spacers 182, 184 such that the electrode110 is raised above the spacers 182, 184 as illustrated schematically inFIG. 1. Alternatively, the outer diameter of the spacers 182, 184 may begreater than the outer diameter of the electrodes 110 such that theelectrodes are recessed.

The lead 106 can include one or more lumens disposed through at least aportion of the length of the lead, as illustrated schematically in FIG.3. The lumens can be formed in a lumen tube 176. A cross-sectional viewof the lumen tube 176 of FIG. 3 at line 4-4 is illustrated schematicallyin FIG. 4. The lumen tube 176 may be made of any non-conductivebiocompatible material including, for example, silicone, polyurethane,and polyetheretherketone (PEEK). In some embodiments, the lead 106includes one or more peripheral lumens 180 (see FIGS. 3 and 4). In atleast some embodiments, the number of peripheral lumens 180 is equal tothe number of electrodes 110.

The lead 106 may also include a central lumen 178 as illustrated inFIGS. 3 and 4. The central lumen 178 can be configured and arranged toreceive a stylet. In the illustrated embodiment, the peripheral lumens180 are configured and arranged to receive at least one lead wire 186.The peripheral lumens 180 are preferably disposed around thecircumference of the lead 106 and are preferably disposed around thecentral lumen 178, if any, as illustrated schematically in FIGS. 3 and4. As will be recognized by those of skill in the art, otherarrangements of lumens within the lumen tube are also possible.

FIG. 5 is a schematic representation of one embodiment of an electrode110. The electrode 110 includes a unitary ring 160. The unitary ring 160may be made of any conductive bio-compatible material including, forexample, metals, metal alloys (e.g., 80% platinum/20% iridium alloy,MP35N, MP LT, etc.), conductive polymers, and conductive carbon. Theunitary ring 160 has an exterior surface 162, an interior surface 164,and at least two edges 170 disposed between the exterior surface 162 andthe interior surface 164. The unitary ring 160 defines a hollow centerregion 174.

Preferably, the unitary ring 160 is a continuous ring and preferablydoes not have any seams such as weld joints. Such electrodes 110comprising a unitary ring 160 therefore are not susceptible to failuresof weld joints, etc. that hold the electrode together.

The electrode 110 includes a seat 166. The seat 166 is a depression inat least the exterior surface 162 of the unitary ring 160. The seat 166may deform both the exterior surface 162 and the interior surface 164 ofthe unitary ring 160 as illustrated schematically in FIG. 5. The seat166 may be formed by any process including, for example, stamping. Theseat 166 is configured and arranged to accept a lead wire 186 (see FIG.11). Preferably, the seat 166 accepts the terminal end of the lead wire186. The lead wire 186 optionally passed through a lumen (e.g., lumen180 of FIG. 3) of the lead body and may pass through an opening in thelead body or a lumen tube to make contact with the electrode.

In some embodiments, the electrode 110 includes an opening 168 (seeFIGS. 5 and 9). The opening 168 extends from the interior surface 164 ofthe unitary ring to the exterior surface 162 of the unitary ring,intersects the seat 166, and is spaced apart from the edges 170 of theunitary ring as illustrated schematically in FIG. 5. Preferably, theopening 168 is configured and arranged to accept a lead wire 186.

Additionally or alternatively, the electrode 110 can include anindentation 190 (see FIG. 10). The indentation 190 extends from theinterior surface 164 of the unitary ring to the exterior surface 162 ofthe unitary ring, intersects the seat 166, and intersects an edge 170 ofthe unitary ring as illustrated schematically in FIG. 10. Preferably,the indentation 190 is configured and arranged to accept a lead wire186. It will be recognized that some electrodes with a seat, asdescribed herein, may not include either an opening or indentation.

FIG. 6 is a cross-sectional view of the electrode 110 of FIG. 5 alongline 6-6. FIG. 7 is a front view of the electrode 110 of FIG. 5. Thedistance 192 between the lowest point on the exterior surface 172 of theseat and the exterior surface 162 of the unitary ring (see FIGS. 6 and7) may be less than, equal to, or greater than the diameter of aterminal end of a lead wire, with or without insulation. The distance192 between the lowest point on the exterior surface 172 of the seat andthe exterior surface 162 of the unitary ring is preferably equal to orgreater than the diameter of the lead wire with insulation when theelectrode 110 does not include an opening 168 or indentation 190. Thedistance between the lowest point on the exterior surface 172 of theseat and the exterior surface 162 of the unitary ring is preferablyequal to the diameter of the lead wire without insulation when theelectrode 110 includes an opening 168 or indentation 190.

FIG. 8 schematically illustrates another embodiment of an electrode 110.This electrode 110 does not have an opening 168 or indentation 190. Ifthe electrode 110 does not include an opening 168 or indentation 190,the seat 166 preferably extends from an edge 170 of the unitary ring 160as illustrated schematically in FIG. 8.

FIG. 9 schematically illustrates another embodiment of an electrode 110.This electrode 110 has an opening 168 and a seat 166. As illustrated inFIGS. 9 and 5, the opening can be disposed completely within the unitaryring 160 (i.e., not intersect an edge of the unitary ring). The seat 166can extend away from the opening 168 to an edge 170 of the unitary ring160 as illustrated schematically in FIG. 5. Alternatively, the seat 166can extend away from the opening 168, but be disposed completely withinthe unitary ring 160 (i.e., not intersect an edge of the unitary ring)as illustrated schematically in FIG. 9.

FIG. 10 schematically illustrates yet another embodiment of an electrode110. This electrode 110 has an indentation 190 that intersects an edge170 of the unitary ring 160. The seat 166 extends from the indentation190 away from the edge 170.

The electrode 110 can be made by any method known to those of skill inthe art. For example, the conductive material used to make the electrodecan be formed as a tubing, which can be cut to the desired length. Theelectrode can then be placed over a first mandrel and a support mandrelcan be inserted into the first mandrel to support a stamping process. Astamping device can be used to form a seat. Additionally, the stampingdevice can be used to form an opening or indentation in the electrode ora separate device can be used to form the opening or indentation.

A lead 106 may be made by any method known to those of skill in the art.For example, a lumen tube 176 with a lead wire 186 disposed in at leastone lumen can be slit to form a passage 194 from the exterior surface ofthe lumen tube 176 to a lumen 180, as illustrated schematically in FIG.11A. The lead wire 186 disposed in the slit lumen can then be partiallyremoved from the lumen and threaded through the opening 168 of anelectrode 110 as illustrated schematically in FIG. 11A. Next, theelectrode 110 is slid over the lumen tube, while holding the lead wiretaut. The seat 166 of the electrode 110 can be aligned with the lumentube such that the seat is disposed over the slit in the lumen tube (seeFIG. 11B). The slit in the lumen tube allows the lumen tube material tobe deformed as the electrode is pushed into position. The lead wire isthen disposed in the seat and attached to the electrode 110 by anymethod including, for example, welding (see FIG. 11C). A spacer 182 maythen be slid onto the lumen tube 176 followed by another electrode 110as described above.

If the electrode 110 does not include an opening 168, instead ofthreading the lead wire through the opening, the electrode 110 can beslid over the lumen tube and the lead wire, while holding the lead wiretaut as illustrated in FIGS. 12A-C. Then the lead wire can be disposedin the seat as illustrated schematically in FIGS. 12A-C.

FIG. 13 is a schematic overview of one embodiment of components of asystem for stimulation, including an electronic subassembly 212 (whichmay or may not include the power source 200), according to theinvention. It will be understood that the system for stimulation and theelectronic subassembly 212 can include more, fewer, or differentcomponents and can have a variety of different configurations includingthose configurations disclosed in the stimulator references citedherein. Some or all of the components of the system for stimulation canbe positioned on one or more circuit boards or similar carriers within ahousing of a stimulator, if desired.

Any power source 200 can be used including, for example, a battery suchas a primary battery or a rechargeable battery. Examples of other powersources include super capacitors, nuclear or atomic batteries,mechanical resonators, infrared collectors, thermally-powered energysources, flexural powered energy sources, bioenergy power sources, fuelcells, bioelectric cells, osmotic pressure pumps, and the like includingthe power sources described in U.S. Pat. No. 7,437,193, incorporatedherein by reference.

As another alternative, power can be supplied by an external powersource through inductive coupling via the optional antenna 224 or asecondary antenna. The external power source can be in a device that ismounted on the skin of the user or in a unit that is provided near thestimulator user on a permanent or periodic basis.

If the power source 200 is a rechargeable battery, the battery may berecharged using the optional antenna 224, if desired. Power can beprovided to the battery for recharging by inductively coupling thebattery through the antenna to a recharging unit 210 (see FIG. 13)external to the user. Examples of such arrangements can be found in thestimulator references identified above.

In one embodiment, electrical current is emitted by the electrodes 110to stimulate motor nerve fibers, muscle fibers, or other body tissuesnear the stimulator. The electronic subassembly 212 provides theelectronics used to operate the stimulator and generate the electricalpulses at the electrodes 110 to produce stimulation of the body tissues.FIG. 13 illustrates one embodiment of components of the electronicsubassembly and associated units.

In the illustrated embodiment, a processor 204 is generally included inthe electronic subassembly 212 to control the timing and electricalcharacteristics of the stimulator. For example, the processor can, ifdesired, control one or more of the timing, frequency, strength,duration, and waveform of the pulses. In addition, the processor 204 canselect which electrodes can be used to provide stimulation, if desired.In some embodiments, the processor may select which electrode(s) arecathodes and which electrode(s) are anodes. In some embodiments withelectrodes disposed on two or more sides of the housing, the processormay be used to identify which electrodes provide the most usefulstimulation of the desired tissue. This process may be performed usingan external programming unit, as described below, that is incommunication with the processor 204.

Any processor can be used and can be as simple as an electronic devicethat produces pulses at a regular interval or the processor can becapable of receiving and interpreting instructions from an externalprogramming unit 208 that allow modification of pulse characteristics.In the illustrated embodiment, the processor 204 is coupled to areceiver 202 which, in turn, is coupled to the optional antenna 224.This allows the processor to receive instructions from an externalsource to direct the pulse characteristics and the selection ofelectrodes, if desired.

In one embodiment, the antenna 224 is capable of receiving signals(e.g., RF signals) from an external telemetry unit 206 which isprogrammed by a programming unit 208. The programming unit 208 can beexternal to, or part of, the telemetry unit 206. The telemetry unit 206can be a device that is worn on the skin of the user or can be carriedby the user and can have a form similar to a pager or cellular phone, ifdesired. As another alternative, the telemetry unit may not be worn orcarried by the user but may only be available at a home station or at aclinician's office. The programming unit 208 can be any unit that canprovide information to the telemetry unit for transmission to thestimulator. The programming unit 208 can be part of the telemetry unit206 or can provide signals or information to the telemetry unit via awireless or wired connection. One example of a suitable programming unitis a computer operated by the user or clinician to send signals to thetelemetry unit.

The signals sent to the processor 204 via the antenna 224 and receiver202 can be used to modify or otherwise direct the operation of thestimulator. For example, the signals may be used to modify the pulses ofthe stimulator such as modifying one or more of pulse duration, pulsefrequency, pulse waveform, and pulse strength. The signals may alsodirect the stimulator to cease operation or to start operation or tostart charging the battery. In other embodiments, the electronicsubassembly 212 does not include an antenna 224 or receiver 202 and theprocessor operates as programmed.

Optionally, the stimulator may include a transmitter (not shown) coupledto the processor and antenna for transmitting signals back to thetelemetry unit 206 or another unit capable of receiving the signals. Forexample, the stimulator may transmit signals indicating whether thestimulator is operating properly or not or indicating when the batteryneeds to be charged. The processor may also be capable of transmittinginformation about the pulse characteristics so that a user or cliniciancan determine or verify the characteristics.

The optional antenna 224 can have any form. In one embodiment, theantenna comprises a coiled wire that is wrapped at least partiallyaround the electronic subassembly within or on the housing.

Any method of manufacture of the components of the system forstimulation can be used. For example, the power source and antenna canbe manufactured as described in U.S. Pat. No. 7,437,193. Thesecomponents can then be placed inside the housing (or, alternatively, thehousing can be formed, e.g., molded, around the components).

The above specification, examples and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A lead comprising: a lead body having a distalend; a plurality of electrodes disposed at the distal end of the leadbody, wherein each of the plurality of electrodes comprises a unitaryring and a seat in the unitary ring, wherein the unitary ring has acircumference, an exterior surface, and an interior surface, wherein theseat is a first region of the unitary ring that is radially depressedwith respect to a second region of the unitary ring adjacent the firstregion, wherein the seat extends around a portion of the circumferenceof the unitary ring that is less than an entire extent of thecircumference with the second region of the unitary ring extending inboth clockwise and counter-clockwise directions around a remainingportion of the circumference of the unitary ring relative to the seat,the seat comprising an exterior surface that is contiguous with theexterior surface of the unitary ring; and a plurality of lead wires,each extending along the lead body and attached directly onto, and incontact with, the exterior surface of the seat of a corresponding one ofthe plurality of electrodes producing an electrical coupling between thelead wire and the corresponding one of the plurality of electrodes. 2.The lead of claim 1, wherein at least one of the plurality of electrodesfurther comprises an opening spaced apart from edges of the unitary ringand extending from the exterior surface to the interior surface of theunitary ring, wherein the opening intersects the seat.
 3. The lead ofclaim 2, wherein at least one lead wire extends through the opening ofat least one of the plurality of electrodes.
 4. The lead of claim 1,wherein a terminal end of at least one lead wire is disposed in the seatof at least one of the plurality of electrodes.
 5. The lead of claim 1,wherein the plurality of electrodes are disposed in a spaced apartarrangement along the distal end of the lead body.
 6. The lead of claim1, further comprising a plurality of spacers, wherein the electrodes areseparated by the spacers.
 7. The lead of claim 1, further comprising alumen tube disposed extending through the plurality of electrodes,wherein the lumen tube comprises at least one lumen.
 8. The lead ofclaim 7, wherein the at least one of the plurality of electrodes furthercomprises an opening spaced apart from edges of the unitary ring andextending from the exterior surface to the interior surface of theunitary ring and wherein at least one of the lead wires is disposed inthe lumen of the lumen tube and extends through the opening of the atleast one of the plurality of electrodes.
 9. A system for stimulationcomprising the lead of claim 1 and a control module, wherein at leastone of the lead wires couples the control module to at least one of theplurality of electrodes.
 10. A method of making a lead for stimulation,the method comprising: providing an electrode comprising a unitary ringhaving a circumference, an exterior surface, an interior surface, and aseat, wherein the seat is a first region of the unitary ring that isradially depressed with respect to a second region of the unitary ringadjacent the first region, wherein the seat extends around a portion ofthe circumference of the unitary ring that is less than an entire extentof the circumference with the second region of the unitary ringextending in both clockwise and counter-clockwise directions around aremaining portion of the circumference of the unitary ring relative tothe seat, the seat comprising an exterior surface that is contiguouswith the exterior surface of the unitary ring; disposing a terminal endof a lead wire within the seat of the electrode; electrically couplingthe terminal end of the lead wire by attachment of the terminal enddirectly onto, and in contact with, the exterior surface of the seat ofthe electrode; and disposing the electrode along a distal portion of alead with the lead wire extending within the lead.
 11. The method ofclaim 10, further comprising forming an opening on the electrode,wherein the opening is spaced apart from edges of the unitary ring andintersects the seat.
 12. The method of claim 11, further comprisingdisposing the lead wire through the opening of the electrode.
 13. Themethod of claim 10, further comprising stamping the unitary ring to formthe seat on the electrode.
 14. The method of claim 10, wherein couplingthe terminal end of the lead wire comprises welding the terminal end ofthe lead wire to the seat of the electrode.
 15. A lead comprising: alead body having a distal end; a plurality of electrodes disposed at thedistal end of the lead body, wherein each of the plurality of electrodescomprises a unitary ring and a seat in the unitary ring, wherein theunitary ring has a circumference, an exterior surface, and an interiorsurface, wherein the seat is a first region of the unitary ring having asmaller outer diameter than a second region of the unitary ring adjacentto the first region, wherein the seat extends around a portion of thecircumference of the unitary ring that is less than an entire extent ofthe circumference with the second region of the unitary ring extendingin both clockwise and counter-clockwise directions around a remainingportion of the circumference of the unitary ring relative to the seat,the seat comprising an exterior surface that is contiguous with theexterior surface of the unitary ring; and a plurality of lead wires,each extending along the lead body and attached directly onto, and incontact with, the exterior surface of the seat of a corresponding one ofthe plurality of electrodes producing an electrical coupling between thelead wire and the corresponding one of the plurality of electrodes. 16.The lead of claim 15, wherein at least one of the plurality ofelectrodes further comprises an opening spaced apart from edges of theunitary ring and extending from the exterior surface to the interiorsurface of the unitary ring, wherein the opening intersects the seat.17. The lead of claim 16, wherein at least one lead wire extends throughthe opening of at least one of the plurality of electrodes.
 18. The leadof claim 15, wherein a terminal end of at least one lead wire isdisposed in the seat of at least one of the plurality of electrodes. 19.The lead of claim 15, wherein the plurality of electrodes are disposedin a spaced apart arrangement along the distal end of the lead body. 20.A system for stimulation comprising the lead of claim 15 and a controlmodule, wherein at least one of the lead wires couples the controlmodule to at least one of the plurality of electrodes.